(a) Field of the Invention
This invention relates to a method for effectively controlling cockroaches by use of an atmosphere of ozone, and more particularly to a method for denaturing a roach-aggregation pheromone contained in roach-feces to a roach-repellent substance by introducing ozone into a habitat where the roach-feces lie scattered, to thereby repel cockroaches from a human habitat.
(b) Description of the Prior Art
Hitherto there have been generally known methods for getting rid of cockroaches, which typically adopt: (1) poisonous baits, (2) slow-release chemical sprays or coatings, (3) contact poison chemicals, (4) fumigants and (5) mechanical traps. The methods using chemicals can be hazardous to man and pet animals and the effect of treatment decreases as resistance develops in the cockroaches. Mechanical trapping, i.e. the use of traps, is not efficient.
Cockroaches are known to excrete an aggregation pheromone along with their feces. The roach-aggregation pheromone is the secretion of the rectum of the cockroach and acts as an attractant, especially for larvae or nymphs. Cockroaches have the habit of hiding away in nooks and corners during daytime and crawling about in the night hours. During daytime the cockroaches are enticed by the aggregation pheromone so that they gather in dark places or other hiding places in a kitchen and so on, forming stable populations. It is known that the growth rate of cockroaches is accelerated when such populations are formed as compared with when they live independently.
One of the inventors of this invention has found and formerly reported that the attractant effect necessary for the cockroaches to live in a group, which is brought about by the aggregation pheromone contained in the roach-feces, can be deactivated by exposing the aggregation pheromone to ultraviolet rays or ozone. (Eisei-Dobutsu; Vol. 32, No. 1, pp.29-36, 1981).
The effect of deactivating the aggregation pheromone in the roach-feces as noted above is the side discovery in the experiment which was conducted by the inventors to prove that the cockroaches can be killed by being directly exposed to ultraviolet rays or ozone. To be specific, it has been found that the roach-aggregation pheromone is deactivated by coming in contact with ozone having a concentration of the order of 0.2 ppm, consequently to counteract the attractant effect of the roach-aggregation pheromone. Such deactivation of the roach-aggregation pheromone would be caused by strong oxidative effect of ozone. However, it was merely revealed that the attractant effect is counteracted due to the deactivation of the roach-aggregation pheromone by use of ozone. In other words, only the fact that ozone can denature the roach-feces to a substance having no effect on the cockroaches was presented. That is to say, the use of ozone was by no means envisaged for the purpose of exterminating or repelling the cockroaches.
In the stage of having issued the report on the deactivation of the roach-aggregation pheromone as mentioned above, it has been hitherto inconceivable that the cockroaches can be repelled by exposing the roach-feces to ultraviolet rays or ozone, like the method of killing the cockroaches by use of ultraviolet rays or ozone is not deemed practical in general. To be more specific, the idea of denaturing the roach-feces to a roach-repellent substance capable of getting rid of cockroaches has not been proposed, much less has there been proposed a method of obtaining such a roach-repellent substance by use of ozone.